Electric immersion heater



Nov. 27, 1956 w. G. BUEHNE ELECTRIC IMMERSION HEATER Filed May 19, 1954 m i 3 mw m fnventofi. M///'$ G Baa/me, by W H/s Attorney United States Patent O ELECTRIC IMMERSION HEATER Willis G. Buehne, Louisville, Ky., assignor to General Electric Company, a corporation of New York Application May 19, 1954, Serial No. 430,839

Claims. (Cl. 21938) This invention relates to electric immersion heaters and has as its principal object the provision of a heater of this character having simple effective means for protecting the mounting structure of the heater against corrosion.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly stated, in accordance with one aspect of my invention I provide an immersion heater having a block or layer of hydraulic cement secured to the mounting plate of the heater and covering the surface of the plate which overlies the opening in the tank in which the heater is mounted. The shape of the cement block or layer conforms to the shape of the tank opening and projects into the opening so that its edges are in close proximity to the walls of the opening. Preferably the thickness of the layer is such that it projects into the tank at least as far as the inner surface of the wall surrounding the opening.

For a better understanding of my invention, reference may be made to the accompanying drawing in which:

Fig. l is a fragmentary sectional view taken along the line 1--1 in Fig. 2 showing an immersion heater embodying my invention secured to a water heater tank.

Fig. 2 is a fragmentary plan view of the immersion heater and tank shown in Fig. i.

Fig. 3 is a detailed view showing the cement block or layer forming part of my invention.

Referring to the drawing, and in particular Fig. l, the numeral 1 designates a sheathed heating element of the so called looped or hairpin type. Such heaters are well known in the art and may be formed in any of the various ways now known and bent into the shape desired. Heater 1 preferably comprises a helical resistance wire 2 surrounded by a seamless and bendable metal sheath 3 preferably made of copper from which it is spaced and insulated by a highly compacted mass of granular insulating material 4. Terminals 5 are embedded in the compacted insulating material and extend outwardly from the sheath 3, the inner ends of the terminals being secured by any suitable means to the ends of resistance wire 2. The ends of heater 1 project through suitable openings in a mounting plate 6 preferably made of steel, and are secured thereto by suitable means such as fluid-tight joints formed by silver soldering, for example. Terminals 5 project from the ends of sheath 3 and extend through a terminal block 7 on which are mounted a pair of terminal strips 8. T erminals 5 project through and are welded to terminal strips 8, and by this means terminal block 7 is secured to plate 6.

My immersion heater is adapted to be mounted in an opening in a water heater tank as shown in the drawing. For purposes of illustration, Fig. 1 shows a portion of a tank having a steel tank wall 9, a steel flange 10 forming the opening in which the heater is mounted, and a corrosion resistant lining of cement 11 on the interior of wall 9. Mounting flange 6 includes a central portion "ice which overlies the tank opening and a surrounding flange portion having openings to accommodate the four bolts 12 which secure the heating unit to the tank flange. Preferably a gasket 13 is interposed between flange 10 and the flanged portion of mounting plate 6.

In accordance with my invention I provide simplified and improved means for protecting mounting plate 6 and the inner surface of flange 10 from the corrosive eflfects of hot water in the tank comprising a layer or block of hydraulic cement 14 covering the central portion of plate 6. The layer of cement may be molded on the assembled heater in which case it will adhere to the surface of flange 6 and the portions of heating element 1 with which it is in contact. Alternatively, cement block 14 may be molded separately in a shape such as that shown in Fig. 3, and assembled with heating element 1 with the two legs of the element projecting through opening 15 before mounting plate 6 and terminal block 7 are secured in place.

The shape of block or layer 14 conforms to the shape of the tank opening formed by flange 10, and its cylindrical surface is in close proximity to the wall of the tank opening. When the tank opening is circular as shown the diameter of block 14 should be slightly less than the diameter of the opening, the difference being only enough to permit the block to slide easily into the opening when the heater is assembled on the tank. The thickness of block 14 should be at least as great as the thickness of the wall surrounding the tank opening, the term thickness referring in this case to the dimension along the axis of the opening. Thus the thickness of the opening shown in Fig. 1 is approximately four times the thickness of tank wall 9.

Cement layer 14 does not completely shield the steel surface of the wall forming opening 10 or the surface of mounting plate 6 from contact with water in the tank. However it does neutralize the water which penetrates the clearance between it and the wall of flange 10, and which also seeps through minute cracks in the layer toward mounting plate 6. It is believed that minerals from the cement layer 14 are dissolved in the water which seeps into contact with these metal surfaces, and is thus converted from a corrosive water to a scale depositing protective type water. Because the space between block 14 and the wall of the opening is quite small water therein tends to stagnate and hence remain saturated with the dissolved minerals.

From the foregoing description it will be seen that my invention eliminates the necessity of utilizing relatively expensive corrosion resistant materials, such as brass or copper in making the heater mounting plate or its protective shield. A further advantage is that the cement block disclosed herein also functions to protect the walls of the tank opening against corrosion.

While I have shown and described a specific embodiment of my invention, 1 do not desire my invention to be limited to the particular construction shown and described and I intend by the appended claims to cover all modifications within the true spirit and scope of my invention.

1 claim as my invention:

1. An electric immersion heater of the type adapted to be mounted in an opening in a water heater tank comprising a sheathed heating element, means for mounting said heating element in said opening, and a layer of hydraulic cement covering the portions of said mounting means overlying said opening.

2. An electric immersion heater of the type adapted to be mounted in an opening in a water heater tank comprising a sheathed heating element, a mounting plate having a flange portion and a central portion secured to said heating element, and a layer of hydraulic cement covering said central portion of said plate.

3. An electric immersion heater of the type adapted to be mounted in an opening in a water heater tank comprising a sheathed heating element, a mounting plate for securing said heater in said opening, and a layer of hydraulic cement covering the portion of said plate lying Within said opening When said plate is secured to said tank.

4. An electric immersion heater of the type adapted to be mounted in an opening in a Water heater tank comprising a sheathed heating element, a mounting plate having a flange portion and a central portion secured to said 10 5. An electric immersion heater of the type adapted to LV be mounted in an opening in a Water heater tank comprising a sheathed heating element, a mounting plate joined to said heating element adjacent one end thereof and provided with a flanged portion adapted to be secured to said tank, and a block of hydraulic cement secured to the face of said plate which overlies said opening, said block having a shape corresponding to the shape of the opening and extending therethrough so that all portions of the walls of said opening are in close proximity to the surface of said block.

References Cited in the file of this patent UNITED STATES PATENTS 2,471,609 Charbonneau May 3 l, 1949 2,473,669 White June 21, 1949 2,486,675 Pokras Nov. 1, 1949 2,594,255 Charbonneau Apr. 22, 1952 2,624,829 Dzaack Jan. 6, 1953 

